Clark Antonson, M.D.

Dr. Clark Antonson has been in practice since 1985. Dr. Antonson is a graduate of the University of Nebraska College of Medicine in Omaha. He completed his Residency at the University of Nebraska College of Medicine and his Fellowship at Kansas University Medical Center. He served as Assistant Professor at the University of Kansas Hospital and Kansas City Veteran's Hospital.   Dr. Antonson is Board Certified in Gastroenterology by the American Board of Internal Medicine.

Andrew D. Coen , M.D.

Dr. Andrew D. Coen has been in practice since 2005.  He is a graduate of the University of Nebraska College of Medicine in Omaha. He completed his internship, residency, and fellowship at the University of Utah Medical Center in Salt Lake City.  Dr. Coen is Board Certified in Gastroenterology by the American Board of Internal Medicine.

Mark G. Griffin, M.D.

Dr. Mark G. Griffin has been in practice since 1990. Dr. Griffin is a graduate of the University of Missouri-Kansas City School of Medicine. He completed his Residency at the University of Colorado Health Sciences where he served as a Clinical Instructor, Staff Physician Specialist, and Medical Director at a walk-in Clinic in Denver General Hospital.  Dr. Griffin completed his Fellowship at the University of Kansas Medical Center. Dr. Griffin is Board Certified in Gastroenterology by the America Board of Internal Medicine. 

Matthew J. Hrnicek, M.D.

Dr. Matthew J. Hrnicek has been in practice since 2005.  He is a graduate of the University of Nebraska College of Medicine in Omaha.  He completed his Internship, Residency and Fellowship at the University of Nebraska College of Medicine.  Dr Hrnicek is Board Certified in Gastroenterology by the America Board of Internal Medicine. 

Paul F. Petersen, M.D.

Dr. Paul F. Petersen has been in practice since 1997. Dr. Petersen is a graduate of the University of Nebraska College of Medicine in Omaha. He completed his Residency at St. Louis University Hospital. Dr. Petersen completed his Fellowship at St. Louis University Hospital where he was Chief Fellow.   Dr. Petersen is Board Certified in Gastroenterology by the America Board of Internal Medicine. 

R. James Sorrell, M.D.

Dr. R. James Sorrell has been in practice since 1995. Dr. Sorrell is a graduate of the University of Nebraska College of Medicine in Omaha. He completed his Internship and Residency at the University of Utah Medical Center and his Fellowship at the University of Nebraska College of Medicine.   Dr. Sorrell is Board Certified in Gastroenterology by the America Board of Internal Medicine. 

Gary W. Varilek, M.D., FACG

Dr. Gary W. Varilek joined Gastroenterology Specialties in January 2001.  He received his M.D. degree from Creighton University in Omaha, Nebraska.  He completed his residency in Internal Medicine at Creighton University Affiliated Residency Program followed by a fellowship in Gastroenterology and Hepatology at the University of Iowa. Dr. Varilek remained on faculty at the University of Iowa in the capacity of staff physician and scientist for five years followed by a similar position at the University of Kentucky.  He is board certified in both Internal Medicine and Gastroenterology/Hepatology.  He is a Fellow of the American College of Gastroenterology, and is currently serving on the Board of Governors of the College representing the state of Nebraska.  He also is a member of the American Gastroenterological Association and the Crohn's Colitis Foundation of America.  He currently is a member of the Medical Advisory Committee for the Omaha office of the Rocky Mountain Chapter of the Crohn's Colitis Foundation of America.  Dr. Varilek has been involved in many clinical research studies while at the University of Iowa, University of Kentucky and Gastroenterology Specialties.  He has lectured both locally and nationally on a variety of gastrointestinal topics.  His special interests include inflammatory bowel disease, celiac disease, and colon cancer prevention.

Kerry Bernal, M.D. - Pathologist

Dr. Bernal joined GES as a pathologist in August 2007. She obtained her undergraduate degree from the University of Chicago, and her medical degree from the University of Illinois College of Medicine in Peoria, IL.  She completed her residency in Anatomic and Clinical Pathology at the University of Nebraska Medical Center (UNMC) in Omaha, NE.  Dr. Bernal was a faculty pathologist at UNMC for four years, with various clinical, administrative, and teaching responsibilities. Her particular areas of interest are gastrointestinal and liver pathology.  She is married and has 2 young children.